The present invention relates to a life span detector for a laser diode.
The present invention also relates to a compact disc player (including a laser disc player, a CD-ROM player, and a CD-I player), which has an optical pick-up including the laser diode.
Conventionally, an optical pick-up of a compact disc player includes a laser diode for emitting a laser beam in order to read data, which is recorded on a disc. When electric current passes through the laser diode, the laser diode emits the laser beam. In the case of using the compact disc player for a long time, the laser diode gradually deteriorates and its luminous intensity lowers. Therefore, a laser diode driver circuit for emitting the laser diode is capable of detecting the luminous intensity thereof and raising electric current intensity when the luminous intensity lowers in order to maintain predetermined luminous intensity. If the laser diode further deteriorates (e.g., 5,000 hours or more), it is impossible to maintain the prescribed luminous intensity. In this case, the optical pick-up cannot accurately read data recorded, and sound skip occurs. Finally, the laser diode, whose life span is completed, must be changed because the data recorded cannot be read by the optical pick-up.
However, the conventional compact disc player has no life span detector for a laser diode, so the life span of the laser diode cannot be known until the sound skip has occurred or the data are unable to be read. Thus, in case of completing the life span while important data are read or music is played back, there is possibility of missing the important data or music.